Summary Of Significant Accounting Policies (Policies)	3 Months Ended
Mar. 31, 2026
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation. The consolidated balance sheet as of March 31, 2026 and the related consolidated statements of income (loss) and comprehensive income (loss) and changes in equity for the three months ended March 31, 2026 and 2025 and the condensed consolidated statements of cash flows for the three months ended March 31, 2026 and 2025 are unaudited. In the opinion of management, all adjustments necessary for fair presentation of such consolidated financial statements have been included. Such adjustments consist only of normal, recurring items. Interim results are not necessarily indicative of results of operations for the entire year. The consolidated balance sheet as of December 31, 2025 was derived from Markel Group's audited annual consolidated financial statements. The accompanying consolidated financial statements have been prepared in accordance with United States (U.S.) generally accepted accounting principles (GAAP) and include the accounts of Markel Group and its consolidated subsidiaries, as well as variable interest entities that meet the requirements for consolidation (the Company). All significant intercompany balances and transactions have been eliminated in consolidation. The Company consolidates the results of its non-insurance operating businesses on a one-month lag, with the exception of significant transactions or events that occur during the intervening period. Certain prior period amounts have been reclassified to conform to the current period presentation. The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses, and the disclosure of contingent assets and liabilities. Actual results may differ materially from the estimates and assumptions used in preparing the consolidated financial statements. The consolidated financial statements and notes are presented as permitted by Form 10-Q and do not contain certain information included in the Company's annual consolidated financial statements and notes. For a more complete description of the Company's business and accounting policies, readers are urged to review the Company's 2025 Annual Report on Form 10‑K.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In November 2024, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures. The standard requires disclosure of certain prescribed costs and expenses within the notes to consolidated financial statements. ASU No. 2024-03 becomes effective for the Company's 2027 Annual Report on Form 10-K. The standard only impacts required disclosures and will not impact the Company's financial position, results of operations, or cash flows. The Company is currently in the early stages of evaluating the impact of ASU No. 2024-03 on its disclosures.

Summary Of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2026

Basis of Presentation. The consolidated balance sheet as of March 31, 2026 and the related consolidated statements of income (loss) and comprehensive income (loss) and changes in equity for the three months ended March 31, 2026 and 2025 and the condensed consolidated statements of cash flows for the three months ended March 31, 2026 and 2025 are unaudited. In the opinion of management, all adjustments necessary for fair presentation of such consolidated financial statements have been included. Such adjustments consist only of normal, recurring items. Interim results are not necessarily indicative of results of operations for the entire year. The consolidated balance sheet as of December 31, 2025 was derived from Markel Group's audited annual consolidated financial statements.

The accompanying consolidated financial statements have been prepared in accordance with United States (U.S.) generally accepted accounting principles (GAAP) and include the accounts of Markel Group and its consolidated subsidiaries, as well as variable interest entities that meet the requirements for consolidation (the Company). All significant intercompany balances and transactions have been eliminated in consolidation. The Company consolidates the results of its non-insurance operating businesses on a one-month lag, with the exception of significant transactions or events that occur during the intervening period. Certain prior period amounts have been reclassified to conform to the current period presentation.

The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses, and the disclosure of contingent assets and liabilities. Actual results may differ materially from the estimates and assumptions used in preparing the consolidated financial statements.

The consolidated financial statements and notes are presented as permitted by Form 10-Q and do not contain certain information included in the Company's annual consolidated financial statements and notes. For a more complete description of the Company's business and accounting policies, readers are urged to review the Company's 2025 Annual Report on Form 10‑K.

Recent Accounting Pronouncements

In November 2024, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures. The standard requires disclosure of certain prescribed costs and expenses within the notes to consolidated financial statements. ASU No. 2024-03 becomes effective for the Company's 2027 Annual Report on Form 10-K. The standard only impacts required disclosures and will not impact the Company's financial position, results of operations, or cash flows. The Company is currently in the early stages of evaluating the impact of ASU No. 2024-03 on its disclosures.